This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In a diffraction experiment each set of planes (hkl) with spacing d in the single crystal acts as a monochromator that must satisfy Bragg?s Law. Each set of planes thus gives rise to a single ?reflection? (spot) in the diffraction pattern with extensions which is defined by a crystal disorder, finite dimensions of the crystal and the beam etc., and spectral characteristics of the beam. For polychromatic X-Ray beam (pink beam) spots occur from crystal in Laue diffraction pattern. In proposed experiment we shall measure energy dispersion of a single pulse of the pink beam by a small molecule/ protein crystal and compare it to the spectral characteristics of the undulator. The energy profile of the X-Ray beam reflected by (hkl) plane of the crystal will be studied using Si single crystal analyzer placed after the crystal diffractor.